Here's some thoughts on wind and solar versus coal - I won't say the author is right as I don't know, but my guess is he's pretty well informed:
"It’s all based around Capacity factor, the delivery of power to consumers in KWH compared to Nameplate Capacity and the formula is this:
NP X 24 X 365.25 X 1000 where NP is Nameplate Capacity, 24 hours in a day 365.25 days in a year (leap year the .25) and 1000 to convert from MW to KWH.
This gives the total maximum power. Capacity Factor is actual delivery compared to that figure.
You’ll read at Wiki (and never trust them) that coal fired power has a CF of around 62%. Where they get that number is for EVERY coal fired plant, and that is somewhat erroneous to say the least, because a lot of medium and smaller coal fired plants are used for Peaking Power and Load Following, so they are only delivering their power for part of the hours in a day.
Large scale coal fired power averages a CF of 87.5%, and Nuclear is the best averaging around 92.5% Worldwide, but in the US currently around 96%.
For Wind Power, even though you’ll see some places quoting 40% and some as low as 10%, The current best case average is the U.S. with the most recent technology, and the second most of it in total, that average is around 20%.
For Solar , and here I’m lumping it all in together because it is just such a tiny proportion of total power delivered, (around 0.2% at best) that CF is around 12.5% at best."